Connectors for optical fiber transmission systems are known in the art. Often times it becomes necessary to arrange a plurality of optical fiber connectors in a panel to facilitate multifiber connections. Desirably, devices for holding connectors are mounted in the panel but the connectors themselves are not connected to incoming or outgoing fiber paths until needed to provide service. Commonly used devices which are used to accommodate interconnections are referred to as couplings. One kind of coupling which is mounted in a wiring panel is a buildout system which includes a buildout block and a buildout.
A very much used ferrule connector for terminating and connecting two optical fibers is one which is referred to as an ST.RTM. connector, ST being a registered trademark of AT&T. The ST connector is disclosed, for example, in U.S. Pat. No. 4,934,785 which was issued on Jun. 19, 1990 in the names of T. D. Mathis and Calvin M. Miller. Another popular optical fiber connector is one known as the SC connector. An SC connector is connected to another SC connector through a coupling to which each SC connector is assembled by linear motion only. Another ferrule connector is an FC connector. Two FC connectors are placed in optical connection with each other through a coupling. Each FC connector is assembled to the coupling by turning threadably each FC connector onto an externally threaded portion of the coupling.
There are a number of concerns which must be addressed by optical connection arrangements. It is well known to use connector adapters in panels to receive connectors. Coupling components such as buildout blocks may be received in panels to accommodate connectors to be installed at a future time. The capability exists with presently available buildout systems for connecting a first connector which terminates an incoming or outgoing fiber path to a buildout block to await future connection of a second connector which terminates an outgoing or incoming fiber path. It is desired to provide those kinds of arrangements with the expensive portions such as connectors or buildouts installed when needed for customer service.
Another concern arises because buildout blocks in an optical wiring panel may number in the hundreds or even thousands. With close spacing between adjacent ones in order to conserve space, it becomes difficult to perform installation, replacement or connection steps on the connector adapters or buildout blocks at the rear of panel, or for that matter, in the front of the panel.
Also, attenuators often are needed in the transmission path to reduce the strength of an incoming signal to a required level. Many optical fiber communication systems require a method of decreasing optical power at a reducing station to avoid the saturation of receivers. Such a reduction in power may be accomplished by introducing into the system a device known as an attenuator which is designed to dissipate or to attenuate a controlled fraction of the input power while allowing the balance to continue through the system. Such an attenuator is disclosed in U.S. Pat. No. 5,082,345 in the names of R. R. Cammons, A. W. Carlisle and N. R. Lampert.
Further, it would be desirable to have a buildout provided with an attenuator element which may be assembled simply to a buildout block already in the wiring panel. This avoids an investment in apparatus before the time when a fiber path is put into service, yet provides an organized and relatively, inexpensive arrangement for storage of connector plugs which are mounted in buildout blocks when the buildout blocks are mounted in a panel.
Complicating matters for arranging cylindrical ferrule connections which may include attenuating provisions is the recognition that there is no universally accepted ferrule connector. AT&T's ST connector is used widely, as are the hereinbefore mentioned SC and FC connectors. Desirably, a sought-after interconnection arrangement may be used to accommodate all three of the foregoing connectors. What is needed and what does not seem to be available is a buildout interconnection arrangement which may be used in ferrule connecting arrangements, of any combination of ST, FC and SC connectors.
Such a system of buildouts and buildout blocks for ferrule connectors desirably should be one which is capable of accommodating FC and SC connectors as well as ST connectors. Further, the system should be one for which the decision as to which ferrule connector to use may be postponed, if necessary, until the time that service is required on a particular fiber path or paths.
A buildout system which is capable of accommodating ST as well as FC connectors is disclosed in U.S. Pat. No. 5,067,783 which issued on Nov. 26, 1991 in the name of N. R. Lampert. The Lampert system includes a buildout block which includes a tubular portion having a longitudinally extending keyway formed in a wall thereof and extending from a flanged end which includes track and latching means. Also, the buildout block includes first and second cavities which communicate with each other through an opening in an internally disposed wall with the first cavity opening to the flanged end of the buildout block and the second cavity opening to an opposite end thereof. The system also includes a buildout which includes first and second coaxially aligned tubular portions which extend in opposite directions from a flanged portion which includes means adapted to cooperate with the track and latching means of the buildout block to secure the buildout to the buildout block upon suitable relative motion which is caused to occur between the buildout and the buildout block. The first tubular portion is adapted to be received in the first cavity of the buildout block and the second tubular portion includes means for causing one of the ferrules which is inserted into the second tubular portion to become secured therewithin. An alignment sleeve is disposed in the first tubular portion of the buildout and is adapted to receive in one end an end portion of one of the ferrules which becomes disposed in the tubular portion of the buildout block. In an opposite end thereof is received the other one of the ferrules which becomes disposed in the second tubular portion of the buildout to cause an optical connection to be made between the optical fibers terminated by the ferrules. The sleeve includes a longitudinally extending slot in a wall thereof and the key of the at least one ferrule assembly is received in the keyway of the tubular portion of the buildout block. Although the buildout system of U.S. Pat. No. 5,067,783 is capable of accommodating ST and FC connectors, it cannot accommodate the SC connector which has become very popular.
What is needed and what is sought after is a buildout system which is capable of facilitating connections between combinations of ST, SC and FC connectors. Desirably, the sought after buildout system may include provisions for attenuating optical signals.